Our blue planet Earth has long been regarded to carry full of nutrients for hosting life since the birth of the planet.Here we speculate the processes that led to the birth of early life on Earth and its aftermath, fi...Our blue planet Earth has long been regarded to carry full of nutrients for hosting life since the birth of the planet.Here we speculate the processes that led to the birth of early life on Earth and its aftermath, finally leading to the evolution of metazoans.We evaluate：（1） the source of nutrients,（2） the chemistry of primordial ocean,（3） the initial mass of ocean,and（4） the size of planet.Among the life-building nutrients,phosphorus and potassium play a key role.Only three types of rocks can serve as an adequate source of nutrients：（a） continent-forming TTG（granite）,enabling the evolution of primitive life to metazoans;（b） primordial continents carrying anorthosite with KREEP（Potassium,Rare Earth Elements, and Phosphorus） basalts,which is a key to bear life;（c） carbonatite magma,enriched in radiogenic elements such as U and Th,which can cause mutation to speed up evolution and promote the birth of new species in continental rift settings.The second important factor is ocean chemistry.The primordial ocean was extremely acidic（pH = 1-2） and enriched in halogens（CI,F and others）,S,N and metallic elements（Cd,Cu,Zn,and others）,inhibiting the birth of life.Plate tectonics cleaned up these elements which interfered with RNA.Blue ocean finally appeared in the Phanerozoic with pH = 7 through extensive interaction with surface continental crust by weathering,erosion and transportation into ocean.The initial ocean mass was also important.The birth of life and aftermath of evolution was possible in the habitable zone with 3-5 km deep ocean which was able to supply sufficient nutrients. Without a huge landmass,nutrients cannot be supplied into the ocean only by ridge-hydrothermal circulation in the Hadean.Finally,the size of the planet plays a crucial role.Cooling of massive planets is less efficient than smaller ones,so that return-flow of seawater into mantle does not occur until central stars finish their main sequence.Due to the suitable size of Earth,the dawn of Phan展开更多
In South China, various megascopic symmetrical metazoan fossils were found in the upper Doushantuo （陡山沱） Formation of the Neoproterozoic Ediacaran. The worm-like fossil is characterized by modern taxological anne...In South China, various megascopic symmetrical metazoan fossils were found in the upper Doushantuo （陡山沱） Formation of the Neoproterozoic Ediacaran. The worm-like fossil is characterized by modern taxological annelid, for many metameres, parapodia, one possible tentale, an alimentary canal, and a dorsal vessel. The triradiate discoidal fossils belong to Trilobozoa, and the octaradiate discoidal fossil might be Ctenophora. All these fossils indicate that the megascopic metazoans have appeared in the Doushantuoian of Eidacaran and imply that the symmetrical metazoans must have originated at least 550 Ma ago.展开更多
The indicator values of microfauna functional groups and species for treatment performancewere systematically evaluated based on the continuous monitoring of the entire microfauna communities including both protozoa a...The indicator values of microfauna functional groups and species for treatment performancewere systematically evaluated based on the continuous monitoring of the entire microfauna communities including both protozoa and metazoa over a period of 14 months, in two parallel full-scale municipalwastewater treatment systems in a plant in Beijing, China. A total of 57 species of ciliates, 14 species （units） of amoebae, 14 species （units） of flagellates and4 classes of small metazoawere identified,with Arcella hemisphaerica, Vorticella striata, Vorticella convallaria, Epistylis plicatilis and small flagellates （e.g. Bodo spp.） as thedominant protozoa, and rotifers as thedominant metazoa. The abundance of the sessile ciliateswas correlatedwith the removals of BOD 5 （Pearson＇s r = 0.410, p 〈 0.05） and COD Cr （r = 0.397, p 〈 0.05）while the testate amoebaewas significantly positively related to nitrification （r = 0.523, p 〈 0.01）. At the same time, some other associationswere also identified： the abundances of the large flagellates （r = 0.447, p 〈 0.01）, the metazoa （r = 0.718, p 〈 0.01） and species Aspidisca sulcata （r = 0.337, p 〈 0.05）were positively related to nitrification; the abundance of Aspidisca costatawas correlated to the TN （total nitrogen） removal （r = -0.374, p 〈 0.05 ）; the abundances of the sessile species Carchesium polypinum （r = 0.458, p 〈 0.01） and E. plicatilis （r = 0.377, p 〈 0.05）were correlatedwith the removal of suspended solids.展开更多
The Ediacaran Dickinsonia is well-known for being the only fossil to be assigned to many phyla, ranging from lichens, Cnidaria, Piatyheiminthes, Annelida, and a phylum of its own to a nonmetazoan kingdom. A new specim...The Ediacaran Dickinsonia is well-known for being the only fossil to be assigned to many phyla, ranging from lichens, Cnidaria, Piatyheiminthes, Annelida, and a phylum of its own to a nonmetazoan kingdom. A new specimen from the Ediacaran fine-grained sandstone on the Winter Coast of the White Sea in northern Russia, which has an age of -555 million years ago, preserved convincing internal anatomies of definite animals, comparable with meridionai canals of extant ctenophores （comb jellies）. Additionally, we reconsidered Dickinsonia as a biradiaily symmetrical animal rather than a bilateral one as previously thought. The animal nature of Dickinsonia is, thus, well established and its affinities are most probably allied to ctenophores. This research is not only removing Dickinsonia from Vendobionta, but also bringing the fossil record of ctenophores forward to 20 million years before the Cambrian ＂explosion＂.展开更多
Hypoxic tolerance experiments may be helpful to constrain the oxygen requirement for animal evolution. Based on literature review, available data demonstrate that fishes are more sensitive to hypoxia than crustaceans ...Hypoxic tolerance experiments may be helpful to constrain the oxygen requirement for animal evolution. Based on literature review, available data demonstrate that fishes are more sensitive to hypoxia than crustaceans and echinoderms, which in turn are more sensitive than annelids, whilst mollusks are the least sensitive. Mortalities occur where O_2 concentrations are below 2.0 mg/L, equivalent to saturation with oxygen content about 25% PAL（present atmospheric level）. Therefore, the minimal oxygen requirement for maintaining animal diversity since Cambrian is determined as 25% PAL. The traditional view is that a rise in atmospheric oxygen concentrations led to the oxygenation of the ocean, thus triggering the evolution of animals. Geological and geochemical studies suggest a constant increase of the oxygen level and a contraction of anoxic oceans during Ediacaran-Cambrian transition when the world oceans experienced a rapid diversification of metazoan lineages. However, fossil first appearances of animal phyla are obviously asynchronous and episodic, showing a sequence as： basal metazoans〉lophotrochozoans〉ecdysozoans and deuterostomes. According to hitherto known data of fossil record and hypoxic sensitivity of animals, the appearance sequence of different animals is broadly consistent with their hypoxic sensitivity： animals like molluscs and annelids that are less sensitive to hypoxia appeared earlier, while animals like echinoderms and fishes that are more sensitive to hypoxia came later. Therefore, it is very likely that the appearance order of animals is corresponding to the increasing oxygen level and/or the contraction of anoxic oceans during Ediacaran-Cambrian transition.展开更多
Microtubular metazoan fossils with multi- branches are found at least 4 times from the Sinian (Ediacarian) Doushantuo Formation at Weng’an, Guizhou, China. Their living mode should be the benthonic colony with higher...Microtubular metazoan fossils with multi- branches are found at least 4 times from the Sinian (Ediacarian) Doushantuo Formation at Weng’an, Guizhou, China. Their living mode should be the benthonic colony with higher ability of asexual re- production. The inner of the tube with cross-walls and chamber shows that these fossils are basal or stem- group cnidarians, similar to extinct tabulates. The multi-branching microtubular fossils are real meta- zoan found from Weng’an biota, which is very im- portant for studying the origin and evolvement of metazoan.展开更多
文摘Our blue planet Earth has long been regarded to carry full of nutrients for hosting life since the birth of the planet.Here we speculate the processes that led to the birth of early life on Earth and its aftermath, finally leading to the evolution of metazoans.We evaluate：（1） the source of nutrients,（2） the chemistry of primordial ocean,（3） the initial mass of ocean,and（4） the size of planet.Among the life-building nutrients,phosphorus and potassium play a key role.Only three types of rocks can serve as an adequate source of nutrients：（a） continent-forming TTG（granite）,enabling the evolution of primitive life to metazoans;（b） primordial continents carrying anorthosite with KREEP（Potassium,Rare Earth Elements, and Phosphorus） basalts,which is a key to bear life;（c） carbonatite magma,enriched in radiogenic elements such as U and Th,which can cause mutation to speed up evolution and promote the birth of new species in continental rift settings.The second important factor is ocean chemistry.The primordial ocean was extremely acidic（pH = 1-2） and enriched in halogens（CI,F and others）,S,N and metallic elements（Cd,Cu,Zn,and others）,inhibiting the birth of life.Plate tectonics cleaned up these elements which interfered with RNA.Blue ocean finally appeared in the Phanerozoic with pH = 7 through extensive interaction with surface continental crust by weathering,erosion and transportation into ocean.The initial ocean mass was also important.The birth of life and aftermath of evolution was possible in the habitable zone with 3-5 km deep ocean which was able to supply sufficient nutrients. Without a huge landmass,nutrients cannot be supplied into the ocean only by ridge-hydrothermal circulation in the Hadean.Finally,the size of the planet plays a crucial role.Cooling of massive planets is less efficient than smaller ones,so that return-flow of seawater into mantle does not occur until central stars finish their main sequence.Due to the suitable size of Earth,the dawn of Phan
基金the Science and TechnologyFoundation of Guizhou Province (No. J-2006-2099)the Stadholder Foundation of Guizhou Provincethe SINOPECProject (No. G0800-08-ZS-319).
文摘In South China, various megascopic symmetrical metazoan fossils were found in the upper Doushantuo （陡山沱） Formation of the Neoproterozoic Ediacaran. The worm-like fossil is characterized by modern taxological annelid, for many metameres, parapodia, one possible tentale, an alimentary canal, and a dorsal vessel. The triradiate discoidal fossils belong to Trilobozoa, and the octaradiate discoidal fossil might be Ctenophora. All these fossils indicate that the megascopic metazoans have appeared in the Doushantuoian of Eidacaran and imply that the symmetrical metazoans must have originated at least 550 Ma ago.
基金supported by the Chinese Academy of Sciences(No.KZCX2-YW-JC407)the National Natural Science Foundation of China(No.20921140094)
文摘The indicator values of microfauna functional groups and species for treatment performancewere systematically evaluated based on the continuous monitoring of the entire microfauna communities including both protozoa and metazoa over a period of 14 months, in two parallel full-scale municipalwastewater treatment systems in a plant in Beijing, China. A total of 57 species of ciliates, 14 species （units） of amoebae, 14 species （units） of flagellates and4 classes of small metazoawere identified,with Arcella hemisphaerica, Vorticella striata, Vorticella convallaria, Epistylis plicatilis and small flagellates （e.g. Bodo spp.） as thedominant protozoa, and rotifers as thedominant metazoa. The abundance of the sessile ciliateswas correlatedwith the removals of BOD 5 （Pearson＇s r = 0.410, p 〈 0.05） and COD Cr （r = 0.397, p 〈 0.05）while the testate amoebaewas significantly positively related to nitrification （r = 0.523, p 〈 0.01）. At the same time, some other associationswere also identified： the abundances of the large flagellates （r = 0.447, p 〈 0.01）, the metazoa （r = 0.718, p 〈 0.01） and species Aspidisca sulcata （r = 0.337, p 〈 0.05）were positively related to nitrification; the abundance of Aspidisca costatawas correlated to the TN （total nitrogen） removal （r = -0.374, p 〈 0.05 ）; the abundances of the sessile species Carchesium polypinum （r = 0.458, p 〈 0.01） and E. plicatilis （r = 0.377, p 〈 0.05）were correlatedwith the removal of suspended solids.
基金Zhang Xingliang gratefully acknowledges the financial support by the National Natural Science Foundation of China(Grant NSFC 40402005)the Program for New Century Excellent Talents(NCET)+1 种基金the Program for Changjiang Scholars and Innovative Research Team in Universities(PCSIRT)Joachim Reitner thanks the Deutsche Forschungsgemeinschaft for finacial support(Leibniz award,Re 665/12-1).
文摘The Ediacaran Dickinsonia is well-known for being the only fossil to be assigned to many phyla, ranging from lichens, Cnidaria, Piatyheiminthes, Annelida, and a phylum of its own to a nonmetazoan kingdom. A new specimen from the Ediacaran fine-grained sandstone on the Winter Coast of the White Sea in northern Russia, which has an age of -555 million years ago, preserved convincing internal anatomies of definite animals, comparable with meridionai canals of extant ctenophores （comb jellies）. Additionally, we reconsidered Dickinsonia as a biradiaily symmetrical animal rather than a bilateral one as previously thought. The animal nature of Dickinsonia is, thus, well established and its affinities are most probably allied to ctenophores. This research is not only removing Dickinsonia from Vendobionta, but also bringing the fossil record of ctenophores forward to 20 million years before the Cambrian ＂explosion＂.
基金supported by National Basic Research Program of China (No. 2013CB835002)National Natural Science Foundation of China (No. 41272036)
文摘Hypoxic tolerance experiments may be helpful to constrain the oxygen requirement for animal evolution. Based on literature review, available data demonstrate that fishes are more sensitive to hypoxia than crustaceans and echinoderms, which in turn are more sensitive than annelids, whilst mollusks are the least sensitive. Mortalities occur where O_2 concentrations are below 2.0 mg/L, equivalent to saturation with oxygen content about 25% PAL（present atmospheric level）. Therefore, the minimal oxygen requirement for maintaining animal diversity since Cambrian is determined as 25% PAL. The traditional view is that a rise in atmospheric oxygen concentrations led to the oxygenation of the ocean, thus triggering the evolution of animals. Geological and geochemical studies suggest a constant increase of the oxygen level and a contraction of anoxic oceans during Ediacaran-Cambrian transition when the world oceans experienced a rapid diversification of metazoan lineages. However, fossil first appearances of animal phyla are obviously asynchronous and episodic, showing a sequence as： basal metazoans〉lophotrochozoans〉ecdysozoans and deuterostomes. According to hitherto known data of fossil record and hypoxic sensitivity of animals, the appearance sequence of different animals is broadly consistent with their hypoxic sensitivity： animals like molluscs and annelids that are less sensitive to hypoxia appeared earlier, while animals like echinoderms and fishes that are more sensitive to hypoxia came later. Therefore, it is very likely that the appearance order of animals is corresponding to the increasing oxygen level and/or the contraction of anoxic oceans during Ediacaran-Cambrian transition.
基金supported by the National Natural Science Foundation of China(Grant No.440272015)the China Geology Survey(Grant No.1212010511607)0pen Laboratory of Chinese Academy of Geological Sciences(Grant No.KL05-4).
文摘Microtubular metazoan fossils with multi- branches are found at least 4 times from the Sinian (Ediacarian) Doushantuo Formation at Weng’an, Guizhou, China. Their living mode should be the benthonic colony with higher ability of asexual re- production. The inner of the tube with cross-walls and chamber shows that these fossils are basal or stem- group cnidarians, similar to extinct tabulates. The multi-branching microtubular fossils are real meta- zoan found from Weng’an biota, which is very im- portant for studying the origin and evolvement of metazoan.
